Re: linux-next boot error: WARNING: workqueue cpumask: online intersect > possible intersect

From: Tejun Heo
Date: Tue Jun 11 2019 - 14:56:42 EST


On Fri, Jun 07, 2019 at 10:45:45AM +0200, Dmitry Vyukov wrote:
> +workqueue maintainers and Michael who added this WARNING
> The WARNING was added in 2017, so I guess it's a change somewhere else
> that triggered it.
> The WARNING message does not seem to give enough info about the caller
> (should it be changed to WARN_ONCE to print a stack?). How can be root
> cause this and unbreak linux-next?

So, during boot, workqueue builds masks of possible cpus of each node
and stores them on wq_numa_possible_cpumask[] array. The warning is
saying that somehow online cpumask of a node became a superset of the
possible mask, which should never happen.

Dumping all masks in wq_numa_possible_cpumasks[] and cpumask_of_node()
of each node should show what's going on.